Economic production of Brassica spp. hybrids requires a pollination control system and effective transfer of pollen from one parent to the other. The ogura cytoplasmic male sterility (cms) system, developed via protoplast fusion between radish (Raphanus sativus) and rapeseed (Brassica napus) is one of the most promising methods of hybrid production. It provides stable expression of the male sterility trait (Ogura 1968), Pelletier et al. (1983) and an effective nuclear restorer gene (Heyn 1976).
Initial restorer material showed reduced female fertility which was overcome through backcrossing. Delourme et al. (1991) attributed this to elimination of a portion of the radish chromosome that had been introduced along with the restorer gene. In their work, successive backcross generations produced fertility levels successively closer to normal.
High glucosinolate (GSL) content in seed of Brassica napus is an anti-nutritional factor. Meal made from such seed is unsuitable for use in animal feeds. Seed GSL level is an expression of the genotype of the female plant and is determined by four to eight separate dominant and additive genes. Two to five genes are involved in alkenyl (one of the aliphatic group) glucosinolate content, while two or three genes are involved in indole glucosinolate content (Rucker and Robbelen, 1994). Total aliphatics may be determined by up to six genes (Magrath et al. 1993).